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  Volume 5, Number 2, April 2020, pages 111-125
DOI: https://doi.org/10.12989/acd.2020.5.2.111
 
open access

A comparative analysis of sheeting die geometries using numerical simulations
Dastan Igali, Dongming Wei, Dichuan Zhang and Asma Perveen

 
Abstract
    The flow behavior of polymer melts within a slit die is an important consideration when designing a die geometry. The quality of the extruded polymer product can be determined through an evaluation of the flow homogeneity, wall shear rate and pressure drop across the central height of the die. However, mathematical formulations cannot fully determine the behavior of the flow due to the complex nature of fluid dynamics and the nonlinear physical properties of the polymer melts. This paper examines two slit die geometries in terms of outlet velocity uniformity, shear rate uniformity at the walls and pressure drop by using the licensed computational fluid dynamics package, Ansys POLYFLOW, based on the finite element method. The Carreau-Yasuda viscosity model was used for the rheological properties of the polypropylene. Comparative analysis of the simulation results will conclude that the modified die design performs better in all three aspects providing uniform exit velocity, uniform wall shear rates, and lower pressure drop.
 
Key Words
    polymer; slit dies; sheeting dies; coat-hanger dies; Carreau-Yasuda viscosity model; three-dimensional FEM simulations; Ansys POLYFLOW; pressure drop; flow homogeneity
 
Address
Dastan Igali and Asma Perveen: Department of Mechanical & Aerospace Engineering, School of Engineering & Digital Sciences, Nazarbayev University, Nur-Sultan city 010000, Republic of Kazakhstan
Dongming Wei: Mathematics Department, School of Sciences and Humanities, Nazarbayev University, Nur-Sultan city 010000, Republic of Kazakhstan
Dichuan Zhang: Department of Civil & Environmental Engineering, School of Engineering & Digital Sciences, Nazarbayev University, Nur-Sultan city 010000, Republic of Kazakhstan; Nur-Sultan city 010000, Republic of Kazakhstan
 

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